1. Statement of the Technical Field
The inventive arrangements relate to portable electronic communications devices, such as cellular phones, smart phones, and personal digital assistants (PDAs), capable of operating in half-duplex communications modes such as push to talk (PTT).
2. Description of Related Art
Some types of portable electronic communications devices transmit and receive radio-frequency (RF) energy in a communication mode known as “half duplex.” In the half-duplex communications mode, signal transmission can occur in two directions, i.e., to and from each user. The signal transmission, however, can occur in only one direction at a time. To facilitate transmission in a particular direction, the user of the transmitting device typically actuates a button or key on his or her communications device. The button or key, when actuated, generates an input that is interpreted by the communications device as a transmit command. This mode of operation is commonly referred to as push-to-talk or PTT.
PTT is a form of half-duplex communication that is frequently used in land mobile radio (LMR) devices. LMR devices are a class of radio equipment designed for use by mobile government and commercial users to communicate, usually on land. For example, LMR devices are commonly used by emergency responders such as firefighters and paramedics; construction crews; security guards; etc.
Portable electronic communications devices, such as PDAs, cellular phones, and smart phones, i.e., cellular phones with enhanced computing functionality and connectivity capabilities, are in widespread use. Most of the portable electronic communications devices currently in use do not have the capability to operate in the half-duplex mode. For example, most cellular phones, smart phones, and PDAs are not equipped with any means to generate a PTT user input corresponding to the transmit command required for half-duplex operation. To the extent these devices can be adapted, through software modifications, to generate such a command based on an input from a touch-screen, such an approach is not practical because it can be difficult for a user to hold his or her finger over a particular location on a touch screen on a repetitive and prolonged basis, as may be required during PTT, LMR, and other half-duplex modes of operation.
Moreover, the speakers and microphones of many cellular phones, smart phones, and PDAs are not suitable for operation with the high background noise levels that are often present during operation of LMR devices. Also, the relatively high power consumption of LMR communications devices can make the battery life of a cellular phone, smart phone, or PDA operating in these modes unacceptably short.